dselect Documentation for Beginners
Chapter 3 - A Few Hints in Conclusion

You can get an idea of the size of a package by hitting i twice and
looking for the ``Size'' figure. This is the size of the compressed package,
so the uncompressed files will be a lot bigger (see ``Installed-Size'', which
is in kilo-bytes, to know it).

Installing a new Debian system is a fairly complex mission, but
dselect can help you do it, if you are prepared to take the time
to learn how to `drive' it. Read the help screens and experiment with i,
I, o, and O. Use the R key. It's all there, but it's
up to you to use it effectively.